Growth of General and Special Ability in Children

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Growth of General and Special Ability in Children!

Growth in abilities is really about as well recognized a phenomenon as growth in height; everyone knows that a 10-year-old child can do many more things, and more difficult things, than a 5-year-old. And a 15-year- old is still more competent.

But there are many important questions regarding growth in ability which general observation cannot an­swer. Does ability grow at a regular rate and in a consistent fashion like height? Growth in height ceases around 18 or 20; does ability also stop growing, perhaps at about the same age?

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An answer in the affirmative might seem somewhat distressing! Height, weight, and strength showed acceleration in rate of growth at adolescence; is there such acceleration in ability? Are there sex differences? Do girls mature more rapidly in ability as they do in physique? Do men finally much exceed girls, as they do in strength? How do dull people differ from bright, in mental growth? Are dull people what they are because they grow more slowly in ability or stop growing sooner, or both? These are all questions of decided importance for education. And they are questions whose answers must quite clearly be obtained from the use of tests, in spite of their shortcomings mentioned in the preceding section. What, then, are the test findings regarding the general trend of growth in ability?

Growth of General Ability:

Chart 4.2 shows typical results. Growth in ability apparently proceeds more or less regularly through child­hood and adolescence; adolescence seems to have no clear effect on it. But the curves level off during later adolescence. At what age this level is reached is a matter of dispute. As already mentioned, Terman assumes a mental age of 15 as the mental level of the average adult. Other investigators have suggested that mental maturity is leached as early as 13 (giving the average adult only a 13-year mentality) or as late as 20. The present trend of thinking is toward these later years.

Testing in the Army in 1918 indicated adult mental level to be between 13 and 1.4. This was about the average age of leaving school at that time. Now, however, average age of leaving school and findings regarding adult level have both gone up Further, when the 1918 results were analyzed with reference to average test score in the different states, high correlations were found (.72) between these state scores and ratings of the quality of the schools in 1900—when most of these men were in school—in these states (Bagley).

In short, the level of ability finally reached, as measured by the tests, appears to be affected by schooling. But it must also be noticed that the general trend of the curve of growth of ability is very similar to the curve of growth in height. That is, a basic background biological growth factor appears to be involved here.

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These are the important findings regarding the growth of ability as measured by tests. But it is clear from the chart that different tests give somewhat different results and that findings must be regarded as rough. Thus there may perhaps be some effect of adolescence upon growth of ability which the tests are too inadequate to show. An adolescent lift for girls around puberty is often found, as in one set of data in the chart. There is no evidence for any general superiority of one sex over the other; apparently the sexes are equal in “ability in general.”

Chart 4.2—Growth in general ability as shown by an individual interview test of the Binet type (Wechsler), and a battery of group tests given to the same individuals at yearly intervals over a nine-year period. (Adapted from data of Wechsler [58] and Freeman [18.)

Individual Differences in Growth:

Do dull children grow more slowly in ability than do the bright? Does their growth continue for a shorter time? Or do “slow” youngsters continue their development for a somewhat longer period and as a result tend somewhat to catch up? Evidence regarding these questions is admirably presented in Chart 4.3. It combines certain data from England and this country and is valuable because of both the consistency of the findings from these two sources and the relating of the test data to other evidences of ability.

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Thus the higher group is made up of persons who had demonstrated their ability by having won scholarships; the English group of mental defectives were, or had been, in special schools for mentally defective children. The American defectives had been diagnosed as of very low mentality on the basis of various evidence.

As will be seen, the chart shows the dull and bright cases growing further and further away from each other with increasing chronological age. Thus the difference between the English children who later won scholarships and those who were put in classes for the mentally defective was only about four years of “mental age” at age 6. But at 18 these two groups were almost twelve years of mental age apart.

Apparently the bright grow in ability more rapidly than the dull. And the mentally superior individuals also appear to continue growth somewhat longer. In fact, the curves for the most defective individuals appear early to go into a decline. Quite clearly, then, the problem of adjustment to individual differences becomes increasingly severe with increase in age.

Chart 4.3— Differences in curves of mental growth of children with different amounts of abilities, from superior children who v on scholarships, to idiots in an institution for the feeble-minded. (From Burt [8], p. 650; the lower two curves from F. Kuhlman. The results of repeated mental examinations of 639 feeble-minded over a period of ten years, J. Appl. Psychol., 1921,5, 195-224.)

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Do children usually grow in ability at a steady and consistent rate, or may one child show a spurt of growth while another lags and drops behind his fellows? Such variations in rate of growth would evidently involve changes in I.Q. As mentioned earlier in this article, the l. Q. of most children is relatively constant. That is, a boy who at 8 has a mental age of six is not likely to show any later period of rapid mental growth which brings him up to average. As shown in Chart 4.4 considerable shifts may occur, however.

When these five boys were all 7—0 years old chronologically, they all had the same mental age of 6—5 and hence the same I.Q. of 92. But ten years later one of these boys tested at only 13—6, whereas another was five and a half years further ahead according to the testi and showed a mental age of 19. “Since these cases were drawn at random and there was no selective factor other than identical mental ages at identical chronological ages, we may assume that such variability is a common occurrence—a fact which numerous other graphs corroborate and which fur­ther statistical studies have emphasized”.

Growth in Special Abilities:

Chart 4.5 shows growth curves for certain special abilities which are similar in general trend to the curves for general ability exhibited in the preceding section; growth is rapid and fairly consistent through the years of physical growth, and tends to level off with the approach to physical maturity.